The composition of injective functions is injective.

If \(g \circ f\) is injective, then \(f\) is injective.

If \(g \circ f\) is surjective, then \(g\) is surjective.

The composition of injective functions is injective.

If \(g \circ f\) is injective, then \(f\) is injective.

If \(g \circ f\) is surjective, then \(g\) is surjective.